GARD Definition: Barth syndrome is a metabolic and neuromuscular disorder, occurring exclusively in males, that primarily affects the heart, immune system, and growth. It typically becomes apparent during infancy or early childhood, but the age of onset, associated symptoms and findings, and disease course varies considerably among affected individuals. The main characteristics of the condition include abnormalities of heart and skeletal muscle (cardiomyopathy and skeletal myopathy); low levels of certain white blood cells called neutrophils that help to fight bacterial infections (neutropenia); and growth retardation, potentially leading to short stature. Other signs and symptoms may include increased levels of certain organic acids in the urine and blood (such as 3-methylglutaconic acid), and increased thickness of the left ventricle of the heart due to endocardial fibroelastosis, which can cause potential heart failure. It is caused by mutations in the TAZ gene and is inherited in an X-linked recessive manner. Treatment is directed toward the specific symptoms that are apparent in each individual. - this information is from GARD/ORDR/NCATS.